Automatic circuit interrupter



Sept.- 1, 1970 K. H. DATE AUTOMATIC CIRCUIT INTERRUPTER 5 sheets-sheet 1Filed April 10. 1968 Sept. 1, K DATE v AUTOMATIC CIRCUIT INTERRUPTER IFiled April 10. 1968 5 Sheets-Sheet 2 P 1970 K. H. DATE AUTOMATIC cacurw INTERRUPTER 5 Shets-Sheet 5 mad April 10, 1968 mun u nul 1 5w i/my 2 I ,B y ac/ 1am! I C;

Sept. 1, 1910 K H. DATE 3,526,860

AUTOMATIC CIRCUIT INTERRUPTER Filed hpril 10, 1968 5 Sheets-Sheet 4.

I l wezuor' 2y mm c Q Sept. 1, 1910 K. H. DATE AUTOMATIC CIRCUITINTERRUPTER Filed April 10, 1968 5 Sheets-Sheet 6 United States Patent3,526,860 AUTOMATIC CIRCUIT INTERRUPTER Kazuo Henry Date, SouthMilwaukee, Wis., assignor to McGraw-Edison Company, Elgin, L, acorporationof Delaware Filed Apr. 10, 1968, Ser. No. 720,168 Int. Cl.H01h 75/04 US. Cl. 335-26 18 Claims ABSTRACT OF THE DISCLOSURE Anoperating mechanism for opening and closing a contactor. A bell crank issecured to a spring and to the con- This invention generally relates toan operating mechanism for the contactor of an automatic circuitinterrupter of the type commonly known as a recloser. More particularly,the invention relates to an operating mechanism for a vacuum contactorof a recloser.

Reclosers are generally installed in electrical distribution systems ina main line or at the origin of a branch line which in turn suppliesother subsidiary lines that are protected by fuses. In the event that afault occurs on the load side of a recloser, the recloser executes oneor more fast opening andone or more relatively delayed reclosingoperations. The relationship of the fault current to the time requiredfor opening the interrupter during the fast openingoperations is suchthat the recloser is faster than the melting time-current characteristicof the fuse so the recloser itself is relied upon as a sole means toclear the fault without damage to the fuse. Most faults are clearedwithout melting the, fuse during the fast opening operations. Ininstances vwhere the fault is not cleared duringa fast Opening sequence,the delayed reclosing operations will take place. The delayedreclosingoperations are obtained by presetting the recloser toautomatically change its time-current characteristic so that furtheropening operations are retarded to provide sufficient time to melt .thefuse. If the fault clears due to melting of the fuse during any of thesuccessive delayed operations, the recloser closes and maintains poweron the line. If the fault is not cleared during the total sequence ofopening and closing operations, the recloser will automatically lock it-.self out and disconnect the branch line being protected from itssource. In order to properly coordinate a particular' recloser withother reclosers and fuses it is necessary that the recloser. have apredictable time-current characteristic. a

. The above discussion applies equally to reclosers utilizing either.oil type interrupting contactors or vacuum contactors. With the adventof vacuum contactors, it has become desirable to develop a vacuumcontactor and contactor operating mechanism which can be interchangedwith the older oil type contactors and associated operating mechanismsso that the latter can be readily converted to vacuum contactor typereclosers. One of the requirements of reclosers using vacuum contactorsis that the operating mechanism for the vacuum contactor be balanced orcompensated for the difference in the operating force due to thedifference between the pressure in the vacuum container and the pressureexternal the container.

A major problem in prior art reclosers is that of assuring optimumprecision and uniformity insofar as time current characteristics andpositive operation are con- 3,526,860 Patented Sept. 1, 1970 cerned.Precise and uniform operation is diflicult to obtain because ofunpredictable dynamics over a widely varying range of currents betweenminimum trip current and maximum fault current. A further problemrelated to the conversion of the recloser to a vacuum contactor type isthat of matching the operating characteristics of the vacuum contactoroperating mechanism to those of the oil contactor operating mechanism.

It is accordingly an object of the invention to provide a contactoperating mechanism having precise and predictable dynamics over thefull current range of the interrupter rating.

Another object of the invention is to provide a recloser contactoperating mechanism that will actuate precisely without being affectedby the friction of the moving components.

Another object of the invention is to provide a recloser operatingmechanism that is particularly suitable for operation of a vacuumcontactor and that has precise and predictable actuatingcharacteristics.

Another object of the invention is to provide a vacuum contactoroperating mechanism which is interchangeable with an oil type contactoroperating mechanism in a recloser and which has the same time-currentcharacteristic and sequential operating characteristic as the oil typecontactor and interrupting mechanism.

A still further object of the invention is to provide a vacuum contactorand snap action operating mechanism for clearing fault with greatrapidity and which is simple in form, economical to manufacture and easyto maintain or replace.

The above stated objects are accomplished by providing an insulated bellcrank lever attached to a vacuum contactor connected in the circuit tobe interrupted and a spring biased overtoggle arrangement acting to holdthe bell crank lever and the vacuum contactor in a closed position and,when overtoggled, to open the contactor. A lever arm is attached to theovertoggle arrangement and is moved to actuate the overtogglearrangement and impact the bell crank lever when a solenoid operatedplunger pushes against tre lever arm. When overtoggle occurs and thebell crank lever is impacted, the vacuum contactor and bell crank leverare forced to their open positions. After the circuit is opened by thevacuum contactor, the opening springs will contract to return theplunger back to its original position and simultaneously close thevacuum contactor at the last or unimpeded part of the plunger stroke.

Other objects and advantages of the invention will in part be obviousand will in part appear hereinafter. For a fuller understanding of thenature and objectsof the invention, reference should be had to thefollowing detailed description taken in connection with the followingdrawings in which:

FIG. 1 is a vertical sectional elevational view, with parts broken away,of a reclosing circuit interrupter assembly embodying the invention;

FIG. 2 is a side sectional view, with parts broken away, showing thecontactor operating mechanism and vacuum contactor of the circuitinterrupter as they ap pear when in normal or closed circuit condition;

FIG. 3 isa side sectional view, with parts broken away, of the contactoroperating mechanism and vacuum contactor of the circuit interrupter asthey appear following occurrence of a fault and just prior to actuationof the operating mechanism and opening of the vacuum contactor;

FIG. 4 is a side sectional view, with parts broken away, of thecontactor operating mechanism and vacuum contactor of the circuitinterrupter as they appear after occurrence of a fault and subsequent toactuation of the operating mechanism and opening of the contacts of thevacuum contactor;

FIG. 5 is another side sectional view, with parts broken away, of thecontactor operating mechanism and vacuum contactor of the circuitinterrupter showing the position of the operating mechanism and vacuumcontactor after both have operated and just after the operatingmechanism has acted to return the actuating plunger to its normalposition;

FIG. 6 is an end view of the contactor operating mechanism and thevacuum contactor; and

FIG. 7 is a top view, with parts broken away, of the contactor operatingmechanism.

Referring to the drawings,.the general construction of the reclosercircuit interrupter includes a metal tank 2 filled with dielectric fluidsuch as oil, a lock-out mechanism 4, a hydraulic timing means 6, anelectromagnetic coil 8 having a plunger 10' engaging the hydraulictiming means 6, a vacuum contactor 12 and a contactor operatingmechanism 14 attached to the vacuum contactor 12 and actuated by theplunger 10. The metal tank 2 is provided with a cover 16 having a pairof bushings 18, only one of which is shown, for the purpose of seriallyconnecting the recloser in a power line. The current path through therecloser between the two bushings 18 constitutes a series circuitincluding the electromagnetic coil 8 and the vacuum contactor 12. Forthe sake of clarity, the lead wires extending through the bushings 18and connecting the electromagnetic coil 8 and vacuum contactor 12 areomitted. The upper end 20 of the plunger 10 is adapted to be drawndownwardly into coil 8 when a current value above minimum trip passesthrough the coil. Movement of the plunger 10 downwardly actuates theoperating mechanism 14 and causes opening of the vacuum contactor -12 toopen the series circuit and de-energize the coil 8.

Following opening of the circuit, the operating mechanism 14 acts toreturn the plunger 10 to its uppermost position and cause the vacuumcontactor 12 to reclose the circuit and again energize the coil 8. Theoperation and construction of the operating mechanism 14 will bediscussed in detail later in this specification.

Each time the plunger 10 descends it pumps a measured quantity of oilwhich in turn causes a predetermined degree of advancement of the trippiston stem 22. After a predetermined number of such operations, thetrip piston stem 22 advances to engage and release the latch finger 24which comprises part of the lock-out mechanism 4. Releasing of the latchfinger 24 results in operation of the lock-out mechanism 4 to cause theplunger 10 to descend and permanently hold the contact operatingmechanism 14 in its open position in which the vacuum contactor 12 isheld open. The plunger 10 may thereafter be released to allow thecontactor 1-2 to close only by a manual reset provision (not shown)comprising part of the lock-out mechanism 4. The features of thelock-out mechanism 4 and hydraulic timing means 6 are well known in theart and, if desired, a detailed description of their construction andoperation maybe found in U.S. Pat. No. 2,926,228, issued to K. H. Dateet al. on Feb. 23, 1960, and assigned to the instant assignee.

The construction and operation of the vacuum contactor 12 and thecontactor operating mechanism 14 will now be discussed in detail. Withreference to FIG. 6, a frame assembly 30 comprises part of the recloserand includes side members 32 and two U-shaped members 34 bolted to theside members 32 by bolts 36. The vacuum contactor 12 is positioned atthe lower end of the frame assembly 30 and includes a vacuum container38, a movable contact stem 46 extending from one end of the vacuumcontainer 38 and a stationary contact stem 42 extending from the otherend of the vacuum container 38. The stationary contact stem 42 issupported by bracket 44 which is attached to the side members 32 bybolts 46.

The movable contact stem 40 is supported on the frame assembly 30 by thebracket 48 which is attached to the side members 32 by bolts 50. Themovable contact stem 40 slides through an insulating sleeve 52 which ispositioned between the movable contact stem 40 and the bracket 48. Thepurpose of the insulating sleeve 52 is to guide the movable contact stem40- With a minimum of friction'and wear during its reciprocatingmovement and to prevent parallel current paths and arcing to the bellows66 which seals the interior of the vacuum container 38 from the outsideatmosphere. The stationary contact 54 and movable contact 56 arerespectively aflixed to the stationary contact stem 42 and movablecontact stem 40 within the vacuum container 38. The vacuum contactor 12is connected in series with the power line through the leads 58 and 60respectively connected to the stationary contact stem 42 and movablecontact stem 40. An electrostatic shield 62 surrounds a portion of thebellows 66 and an arc shield 64 is disposed between the contacts 54 and56 and the vacuum container 38 for preventing condensation of vaporizedcontact material on the inner surface of the vacuum container 38.

With reference to FIGS. 2-7, the contactor operating mechanism 14includes a double member lever arm having a pair of congruent levers andadapted to pivot on a fixed transverse bolt 82 spanning between the sidemembers 32. The lever arm 80 carries a roller 86 which engages andreceives force from plunger 10 when plunger '10 is moved downwardly bythe electromagnetic coil 8. There is a collapsible linkage 70 having alower-double arm link 88 and an upper link 90 pivotally attached to thelever arm 80 by pin 92 and positioned between the two levers of leverarm 80 by the spacer sleeves 94. The lower double arm link 88 ispivotally connected to the upper link 90 by the pin 96 and is pivotallysupported on the side members 32 of the frame assembly 30 by the pins98.

A double member bell crank lever is pivotally supported at its fulcrum112 on the side members 32 by the pins 114. The 'bell crank lever 110has a lever arm 116 pivotally connected to the movable contact stem 40of the vacuum contactor 12 by the pin 118. The bell crank lever :110 isheld on the machined pin 118 and the movable contact stem 40 is attachedto and centered on pin 118 by cotter pins 120. A pair of overcentercontact springs 124 are secured at their ends to pin 96 which also actsas pivot point for the collapsible linkage 70. The springs 124 are heldin position by spacer sleeves 126 carried on pin 96. The springs 124 arepivotally attached at their other ends to a grooved transverse pin 130.A pair of link arms 128 are pivotally supported on side members 32 bypins 114 and are pivotally connected to the transverse pin 130 adjacentits ends. The ends of the transverse pin 130* are slidably guided withinthe arcuate slots 113-2 formed in the members of bell crank lever 110*.As the drawings indicate, sliding motion of the pin 130 requires thecontact opening springs 124 and the link arms 128 to move along thelength of the arcuate slots 132. The link arms 128 and the bell cranklever 110 are held in a parallel relationship by the washers 136.

A compensating arrangement adapted to counterbalance the operating forcedifference on the operating mechanism' 14 due to the pressuredifferential external the vacuum container 38 and the pressure withinthe vacuum container 38 includes a counterbalancing linkage having apair of upper link arms and a pair of lower link arms 152 (see FIGS. 2-5and 7). The lower link arms 152 are pivotally connected at their lowerends by pin :154 to an end of the lever arm 134 of the bell crank lever110. The pin 154, supported on bell crank lever 110, also carries theroller 156 against which the roller 86 impacts when the lever arm 80 ispushed down by the plunger 10. The spacer sleeves 158 are supported onpin 154 and maintain the link arms 152 and the roller 156 in theirproper relationships (see FIG. 7). The upper link arms 150 are pivotallyanchored to the side members 32 by pins 160. The upper link arms 150 andlower link arms 152 are pivotally connected by transverse pin 164. Thebalancing springs 166 are connected between the transverse pin 164 andthe pin 82 supported on the side members 32.

The operating sequence positions of the contactor operating mechanism 14are shown in FIGS. 2-5. In FIG. 2, the plunger is shown in its upwardposition in which it is held by the force of the contact operatingsprings 124 acting through link arms 88 and 90 and the lever arm 80 whenfault current is not passing through the electromagnetic coil 8. In theposition of the contactor operating mechanism 14 shown in FIG. 2, thecontact operating springs 124 are held in a position above the fulcrum112 of the bell crank lever 1410 by the link arms '88 and 90. In thisposition the transverse pin 130* is held against the upper ends of thearcuate slots 132 by the contact operating springs 124- to pivot thebell crank lever 110 clockwise about its' fulcrum 112 and hold themovable contact stem 40 in its inward position and the contacts 54 and56 in engagement with each other. When the contacts 54 and 56 areengaged, the electrical circuit in 'which they are connected is closed.In the position of the bell crank lever 110 shown in FIG. 2,counterbalancing linkage 140 acts to pivot the bell crank lever 110 in acounter-clockwise direction to compensate for the relative lack ofpressure on the movable contact stem 40 from within the vacuum container38.

FIG. 3 shows the position of the plunger 10, the lever arm 80 and thecollapsible linkage 70 after the plunger 10 has started its downwardmovement but before the contactor operating mechanism 14 has beenactuated to open the contacts 54 and 56. The electromagnetic coil 8 isnow carrying the predetermined amount of overcurrent required to pushthe plunger 10 downward against the lever arm 80 to the point where itimpacts the roller 156 on the bell crank lever 110. Movement of thelever arm 80 downwardly causes the collapisble linkage 70 to collapse tomove the pivot point at pin 96 of the contact operating springs 124below the fulcrum 112 of the bell crank lever 110. When the contactoperating springs 124 are below the fulcrum 112, they apply force to thebell crank lever 110 in a direction which tends to pivot the bell cranklever 110 in a counter-clockwise direction. In addition, the directionof the force now applied by the springs 124 is such that downwardmovement of the pin 130 is no longer impeded due to the arcuate shape ofthe slots 132. The pin 130 will thus snap to the bottom of the slots 132and impact the bell crank lever 110 to provide a snap action overtoggleof springs 124. The impacting of bell crank lever 110 further assists inpivoting the bell crank lever 110 counter-clockwise and moving the slots132 downward to increase the leverage of springs 124 for positivecontact opening operation. The contact opening springs 124 are thussnapped to an overtoggled position which causes them to pivotallysnapthe bell crank lever 110 in a counter-clockwise direction as assisted bythe snap action movement of the transverse pin 130. As is also shown inFIG. 3, the contacts 54 and 56 continue to be in an engaged positionuntil the lower roller 156 is impacted to effect a forceful separatingmovement to contacts 54 and 56. The impacting of the roller 156 takesplace at substantially the same instant that the operating springs 124overtoggle with a snap action so that all contact opening forces occursimultaneously.

In FIG. 4, the contactor operating mechanism 14 is shown after thecontact operating springs 124 have overtoggled and snapped thetransverse pin 130 down to the bottom of the arcuate slot 132 andpivoted the bell crank lever 110 to its position in which the movablecontact stem 40 is moved away from the vacuum container 38 and thecontacts 54 and 56 are opened to interrupt the circuit. It can thus beseen that overtoggle of the contact operating springs 124, the snap ofthe transverse pin 130 against the bottom of the slots 132 and theimpact of the roller 86 on the lever arm against the roller 156 togetherprovide a high speed, forceful pivoting action on the bell crank leverto result in positive bell crank lever movement and opening of thecontacts regardless of friction at the pivoting points in the operatingmechanism and a possible welding of the contacts from high currents.

In FIG. 5, the contacts 54 and 56 are shown in their open position inwhich the power line circuit is opened and the electromagnetic coil 8 isde-energized. Under these conditions the plunger 10 is free to moveupward and is returned to its upward position by contraction of thecontact operating springs 124. A comparison of FIGS. 4 and 5 will showthat when the plunger is in its fully extended downward position thecontact operating springs 124 are in an extended, charged position andare held that way as long as the plunger 10 is held downward by the coil8. When fault current is no longer flowing through the coil 8, theplunger 10 will not hold the contact operating springs 124 in theirextended position and the springs will then contract to open thecollapsible linkage 70 and force the lever arm 80 and plunger 10 upward.The contact operating mechanism 14 will then be in its position shown inFIG. 5. When the pivot point at pin 96 of the contact operating springs124 has moved above the fulcrum 112, the bell crank lever 110 will againbe pivoted about its fulcrum 112 so that it snaps clockwise to itsoriginal position shown in FIG. 2 to close the contacts 54 and 56. Also,as the operating springs 124 overtoggle, the transverse pin connected tothe link arm 128 is snapped upward and the bell crank 110 is pivotedclockwise to close the contacts 54 and 56. The contact operatingmechanism 14 has now completed a contact opening and closing operationincluding a reclosing time delay between opening and closing and isready to recycle in the event of further fault current flow through thecoil 8. If the fault current flow continues, the hydraulic timing means6 will, after a preset number of operations, actuate the look-outmechanism 4 to hold the plunger 10 in its downward position and causethe contact operating mechanism 14 to hold the contacts 54 and 56 openuntil the look-out mechanism 4 has been manually reset.

Although a preferred embodiment of the invention has been illustratedand described, the disclosure is not to be interpreted as limiting, forthe invention may be variously embodied and is to be construed in accordwith the claims which follows.

What is claimed is:

1. The combination with a reclosing circuit interrupter connected in anelectrical circuit and including a contactor means having an open andclosed position for interrupting the electrical circuit, anelectromagnetic coil and a plunger having a normal position relative tosaid coil and being movable from said normal position by theelectromagnetic coil when the coil is energized by an overcurrent valuein the electrical circuit of:

bell crank means directly secured to the contactor means and beingmovable transversely relative to the path of movement of said plungerbetween first and second positions respectively corresponding to theclosed and open positions of the contactor means, said bell crank meansbeing actuated and moved to its second position by movement of theplunger when the electromagnetic coil is energized to move the contactormeans to its open position; and

resilient means directly secured to the bell crank means for returningthe bell crank means to its first position and the contactor means toits closed position sub sequent to actuation of the bell crank means bythe plunger.

2. The combination according to claim 1 wherein said resilient means hasa first position in which it urges the bell crank means and thecontactor means toward their corresponding first and closed positionsand a second 7 position in which it urges the bell crank means and thecontactor means toward their corresponding second and open positions.,

3. The combination according to claim 2 further comprising linkage meanssecured to the resilient means and engaged by the plunger when it ismoved by the coil for moving the resilient means from its first positionto its second position and for returning the plunger to its normalposition after the plunger has actuated the bell crank means to move thecontactor means to its open position.

4. The combination with a reclosing circuit interrupter connected in anelectrical circuit and including an electromagnetic coil and a plungermovable along a path in the direction of its length by theelectromagnetic coil when a predetermined current value flows from theelectrical circuit through the coil of:

contactor means connected in the electrical circuit and being movable toa first position in which the electrical circuit is closed and to asecond position in which the electrical circuit is opened and theelectromagnetic coil is deenergized;

bell crank means pivotally secured to the contactor means and beingmovable between first and second positions respectively corresponding tothe first and second positions of the contactor means, said bell crankmeans being positioned in the path of movement of and actuated by theplunger when the plunger is moved by the electromagnetic coil to movethe contactor means from its first to its second position, whereby theelectrical circuit is opened and the electromagnetic coil deenergized;

resilient means secured to the bell crank means and having a firstposition in which it moves the bell crank means and the contactor meansto their respective first positions and a second position in which itacts together with the plunger to move the bell crank means and thecontactor means to their respective second positions and a secondposition in which it acts together with the plunger to move the bellcrank means and the contactor means to their respective secondpositions, said resilient means also urging the plunger in a directionaway from the bell crank means while the resilient means is in saidsecond position after the electrical circuit is opened and theelectromagnetic coil has ceased to move the plunger; and

linkage means secured to the resilient means, said linkage meansincluding a movable lever arm positioned in the path of movement of theplunger and engaged by the plunger when it is moved by the coil toactuate the linkage means for moving the resilient means from its firstposition to its second position and for engaging and moving the plungeralong said direction away from the bell crank means in response to theresilient means subsequent to the movement of the resilient means to itssecond position and the opening of the electrical circuit.

'5. The combination according to claim 4 wherein:

said contactor means comprises a vacuum contactor having a containerdefining a vacuum space; and including balancing means secured to thebell crank for counterbalancing the force on the vacuum contactor due tothe difference in pressure within said vacuum container and the pressureexterior of the container.

6. The combination according to claim 4 wherein:

said bell crank means includes a fulcrum about which it pivots and alost motion slot spaced from said fulcrum and having a lengthsubstantially transverse to a line extending from said fulcrum; and

said resilient means includes a toggle arm guided within the lost motionslot and being movable between opposite ends of the slot to guide theresilient means between its first and second positions.

7. The combination according to claim 6 wherein said linkagemeansincludes a pair of pivotally connected collapsible link armssecured at their connection to the resilient means and collapsing toextend the resilient means and move the resilient means from its firstto its second position when the linkage means is actuated by the plungerand being extended to return the resilient means to its first positionand move the plunger away from the bell crank means in response tocontraction of the resil ient means after the electrical circuit isopened and the electromagnetic coil has ceased to move the plunger.

8. The combination with an automatic circuit interrupter connected in anelectrical circuit and including an electromagnetic coil and a plungermovable along a path in the direction of its length by theelectromagnetic coil when a predetermined current value flows from theelectrical circuit through the coil of:

contactor means connected in the electrical circuit and being movable toa first position in which the electrical circuit is closed and to asecond position in which the electrical circuit is opened and theelectromagnetic coil is deenergized;

lever arm means pivotally supported on the interrupter and positioned inthe path of movement of the plunger, said lever arm means being engagedand pushed by the plunger when the plunger is moved by theelectromagnetic coil;

bell crank means including two lever arms and a fulcrum pivotallysupported on the interrupter for moving the contactor means between itsfirst and second positions, said bell crank means being pivotablebetween first and second positions respectively corresponding to thefirst and second positions of the contactor means, the first of saidlever arms being attached to the contactor means and the second of thelever arms being positioned in the path of movement of said lever armmeans whereby the lever arm means impacts and pushes the second leverarm when the plunger engages and pushes the lever arm means to pivot thebell crank means and move the contact means to their respective secondpositions; and

resilient means secured to the bell crank means and the lever arm meansand having a first position in which it urges the bell crank means andthe contact means toward their first positions and being movable to asecond position by the lever arm means in which the resilient means actstogether with the plunger to pivot the bell crank means and move thecontact means to their second positions.

9. The combination according to claim 8 wherein said resilient means ischarged in its second position relative to its charge when in its firstposition and acts to discharge itself and return itself, the bell crankmeans and the contactor means to their associated first positions whenthe electromagnetic coil is deenergized and the plunger ceases to pushthe lever arm means.

10. The combination according to claim 8 wherein said resilient meansincludes a collapsible linkage means having an open position in whichthe bell crank means is held in its first position and a relativelyclosed position in which the bell crank means is held in its secondposition until the plunger ceases to push the lever arm means.

11. The combination according to claim 8 wherein:

said contactor means comprises a vacuum contactor including a containerdefining a vacuum space; and including resilient balancing means securedto the bell crank means for counter-balancing the force on the vacuumcontactor due to the difference between the vacuum pressure within saidcontainer and the higher pressure external the container.

12. The combination according to claim 8 wherein:

said bell crank means includes an arcuate shaped lost motion slot spacedfrom the fulcrum and having a length transverse to a line extending fromthe fulcrum; and

said resilient means includes a toggle arm having a free end slidablyguided within the lost motion slot and being movable between oppositeends of the slot to guide the resilient means between its first andsecond positions.

13. The combination according to claim 12 wherein said lost motion slotis positioned along the length of the second lever arm of the bell crankmeans transverse to the length of the second lever arm.

14. The combination according to claim 8 wherein:

said bell crank means includes an arcuate shaped lost motion slot spacedfrom the fulcrum and having a length transverse to a line extending fromthe fulcrum; and

said resilient means includes a toggle arm having a free end slidablyguided within the lost motion slot and being movable between oppositeends of the slot to guide the resilient means between its first andsecond positions, a collapsible linkage means having an open position inwhich the bell crank means is held in its first position and arelatively closed position in which the bell crank means is held in itssecond position until the plunger ceases to push the lever arm means,and a spring connected between the free end of said toggle arm and thecollapsible linkage means, said spring being relatively contracted whenthe resilient means is in its first position and extended and chargedwhen the resilient means is in its second position.

15. The combination according to claim 14 wherein:

said contactor means comprises a vacuum contactor including a containerdefining a vacuum space; and including a resilient balancing meanssecured to the bell crank means for counter-balancing the force on thevacuum contactor due to the difference between the vacuum.

pressure within said container and the higher pressure external thecontainer.

16. The combination according to claim 15 wherein said resilientbalancing means includes a pair of pivotally connected link armsconnected to the bell crank means and having a spring attached to thelink arms at their pivotal connection for applying counter-balancingforce to the bell crank means.

17. The combination according to claim 1 wherein:

said bell crank means includes a first lever arm directly secured tosaid contactor means and a second lever arm, said lever arms each beingmovable transversely relative to each other, said second lever arm beingpositioned in the path of movement of and being moved by the plungerwhen the latter is moved in response to energization of said coilwhereby the contactor means is moved to its open position in a directiontransverse to that of the plunger movement; and said resilient means hasa position in which it simultaneously returns the plunger and thecontactor means to their respective normal and closed positions.

18. The combination according to claim 17 wherein said resilient meanscompress a single spring.

References Cited UNITED STATES PATENTS 3,189,708 6/1965 Heintz 335-262,145,741 l/l939 Stablein et a1. 33526 FOREIGN PATENTS 1,282,733 4/1962France.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner

